Electrolyte solvents and methods for lithium metal and lithium ion batteries

Abstract

A molecular design principle utilizes a steric hindrance effect to tune the solvation structures of Li+ ions. By substituting the methoxy groups on DME with larger-sized ethoxy groups, the resulting 1,2-diethoxyethane (DEE) has weaker solvation ability and consequently more anion-rich inner solvation shells, both of which enhance interfacial stability at cathode and anode. According to certain additional aspects, the present embodiments relate to a family of fluorinated-1,2-diethyoxyethane (fluorinated-DEE) molecules that are readily synthesized in large scales to use as the electrolyte solvents. Selected positions on 1,2-diethyoxyethane (DEE, distinct from the diethyl ether are functionalized with various numbers of fluorine atoms through iterative tuning, to reach a balance between CE, oxidative stability, and ionic conduction. Paired with 1.2 M lithium bis(fluorosulfonyl)imide (LiFSI), these fluorinated-DEE-based, single-salt single-solvent electrolytes are thoroughly characterized. In addition, a family of fluorinated ethyl methyl carbonates are designed and synthesized. Different numbers of F atoms are finely tuned to yield monofluoroethyl methyl carbonate (F1EMC), difluoroethyl methyl carbonate (F2EMC) and trifluoroethyl methyl carbonate (F3EMC). The cycling behavior of several types of lithium-ion pouch cells were systematically investigated to understand the impact of fluorination degree.

1 - 16 . (canceled) 
     
     
         17 : An electrolyte comprising a compound, wherein the compound is
 (i) a fluorinated derivative of 1,2-diethoxyethane, wherein one or more of the hydrogen atoms of the 1,2-diethoxyethane are substituted by fluorine; or   (ii) a fluorinated derivative of 1,1-diethoxymethane, wherein one or more of the hydrogen atoms of the 1,1-diethoxymethane are substituted by fluorine; or   (iii) a fluorinated derivative of 1,3-diethoxypropane, wherein one or more of the hydrogen atoms of the 1,3-diethoxypropane are substituted by fluorine; or   (iv) a fluorinated derivative of dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate, wherein one or more of the hydrogen atoms of the dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate are substituted by fluorine; or   (v) a 1,2-dialkoxy ethane compound, wherein each alkoxy group contains between two and four carbon atoms; or   (vi) a compound selected from the group consisting of selected from the group consisting of   
       
         
           
           
               
               
           
         
       
     
     
         18 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         19 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         20 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         21 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         22 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         23 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         24 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         25 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         26 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         27 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         28 : The electrolyte of  claim 17 , wherein the compound is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
         29 : The electrolyte of  claim 17 , wherein the electrolyte comprises one or more additional components selected from the compounds recited in  claim 17 . 
     
     
         30 : The electrolyte of  claim 17 , wherein the electrolyte comprises a solvent component that is not a compound recited in  claim 17 . 
     
     
         31 : The electrolyte of  claim 30 , wherein the solvent component is selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), vinyl carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), 3,3,3-trifluoropropylene carbonate (TFPC), trifluoroethyl methyl carbonate (FEMC), bis(2,2,2-trifluoroethyl) carbonate (TFEC), 1,2-dimethyoxylethane (DME), 1, 3-di oxolane (DOL), 1,4-di oxane (DOX), tetrahydrofuran (THF), 1,3,2-dioxathiolane-2,2-dioxide (DTD), 1,3-propanesultone (PS), acetonitrile (AN), ethyl acetate (EA), methyl acetate (MA), methyl propanoate (MP), succinonitrile (SN), trimethyl phosphate (TMP), triethyl phosphate (TEP); tris(trimethylsilyl)phosphate (TTSP), tris(2,2,2-trifluoroethyl) phosphate (TFEPa), tris(2,2,2-trifluoroethyl) phosphite (TFEPi), prop-1-ene-1,3-sultone (PES), ethylene sulfite (ES), 1,4-butane sultone (BS), dimethyl sulfoxide (DMSO), methylene methanedisulfonate (MMDS), N,N-Dimethylformamide (DMF), and gamma-butyrolactone (BL). 
     
     
         32 : The electrolyte of  claim 30 , wherein the amount of the solvent component in the electrolyte is between about 5 wt. % and about 99 wt. %. 
     
     
         33 : The electrolyte of  claim 17 , wherein the electrolyte comprises one or more salts. 
     
     
         34 : The electrolyte of  claim 33 , wherein the salt is selected from the group consisting of a lithium salt, a potassium salt, a sodium salt, and mixtures of any of the foregoing. 
     
     
         35 : The electrolyte of  claim 33 , wherein the salt is selected from the group consisting of bis(fluorosulfonyl)imide (LiFSI); lithium bis(trifluoromethanesulfonyl)imide (LiTFSI); lithium hexafluorophosphate (LiPF6); lithium hexafluoroarsenate (LiAsF6); lithium tetrafluoroborate (LiBF4); lithium bis(oxalato)borate (LiBOB); lithium difluoro(oxalato)borate (LiDFOB); lithium difluorophosphate (LiDFP); lithium nitrate (LiNO3); lithium perchlorate (LiClO4); lithium triflate (LiTf); lithium trifluoroacetate (LiTFA); lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI); sodium bis(fluorosulfonyl)imide (NaFSI); sodium bis(trifluoromethanesulfonyl)imide (NaTFSI); potassium bis(fluorosulfonyl)imide (KFSI); and potassium bis(trifluoromethanesulfonyl)imide (KTFSI), and mixtures of any of the foregoing. 
     
     
         36 : An electrochemical cell comprising:
 an anode;   a cathode; and   the electrolyte of  claim 17 .   
     
     
         37 : The electrochemical cell of  claim 36 , wherein the electrochemical cell is a battery. 
     
     
         38 : The electrochemical cell of  claim 36 , wherein the anode comprises lithium. 
     
     
         39 : The electrochemical cell of  claim 36 , wherein the anode comprises lithium metal. 
     
     
         40 : The electrochemical cell of  claim 36 , wherein the anode comprises a surface protection layer comprising fluorine. 
     
     
         41 : The electrochemical cell of  claim 36 , wherein the anode comprises a material selected from the group consisting of lithium metal, graphite, silicon, silicon oxide (SiO x ), graphite/silicon composite, graphite/silicon oxide (SiO x ) composite, graphite/silicon nitride (Si 3 N 4 ) composite, graphite/silicon carbide (SiC) composite, and mixtures of any of the foregoing. 
     
     
         42 : The electrochemical cell of  claim 36 , wherein the cathode comprises the cathode material comprises a sulfur-based cathode or an air cathode (e.g., a Li—S, Li-SPAN, or a Li-air battery), a lithium nickel manganese cobalt oxide (e.g., NMC111, NMC532, NMC622, NMC811, NMC900505, NMC95025025, etc.), a lithium nickel cobalt aluminum oxide (NCA), a lithium nickel manganese aluminum oxide (NMA), a lithium nickel manganese cobalt aluminum oxide (NMCA), a lithium nickel manganese oxide (NM), a lithium nickel oxide (LNO), a lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O 4 , LNMO), a lithium cobalt oxide (LCO), a lithium manganese oxide (LMO), a lithium and manganese rich cathode (LMR or LLMO), a lithium iron phosphate (LFP), a lithium cobalt phosphate (LCP), a lithium manganese phosphate (LMP), a lithium manganese iron phosphate (LMFP), a transition metal sulfide (e.g., FeS, FeS 2 , CuS, MoS 2 , MoS 3 , TiS 2 , TiS 4 , etc.), and mixtures of any of the foregoing. 
     
     
         43 : A compound selected from the group consisting of